Season one set up the characters. There are as many as eight characters
considered principles. Those would be Vic Mackey, Shane Vendrell, and
Curtis Lemansky aka Lem from the special unit Strike Team, their boss Captain
David Aceveda, Detectives Claudette Wymms and Dutch Wagenbach, and representing
the uniformed officers Danny Sofer and Julien Lowe. On top of which, there
are probably about that many major supporting characters.

Season two did more to flesh out those characters. Julien being gay,
for example, basically worked to set up his marriage and attempt at going
straight in seasons two.

Season three gets more complicated, as characters start developing, changing.
Coming up with these changes, and properly motivating them -- THAT shows some
serious SKILL in the writing. Claudette in particular started acting
significantly different than previously after having just a little whiff of
power. Shane and Lem are cracking under the pressure. Then there is
Captain Aceveda and The Incident.

Season four brought in the compassionate but extremely hard nosed Captain
Rawling to bust heads in the hood, with tough enforcement of asset forfeiture
laws, while supposed community activist Antwon Mitchell went crazy killing cops
and children.

We have season five, with a wussy yes-man captain being overrun by the
most evil but "honest" internal affairs character ever in a cop
show. Forest Whitaker is GOOD, and he's getting something to work with.

Now we're into season six, dealing with the aftermath of Lemonhead's murder
by one his own, and the
tension and sense of
doom builds like hot air in
greenhouses for next season's
series finale and settling of
accounts.